Phase I - The major objective of this study will be to provide the parameters and characteristics of genistein's toxicity in post-menopausal women, pharmacokinetic data, the safely delivered dose and a recommended phase II/III dose. The purpose of this research study is to test a soy product called genistein, to learn how it affects the body. To do this, we need to obtain blood samples at specified time points from a few healthy volunteers who have not received genistein, or any other soy product.